This is the peer reviewed version of the following article: Soulsby, C., Bradford, J., Dick, J., McNamara, J. P., Geris, J., Lessels, J., Blumstock, M., and Tetzlaff, D. (2016) Using geophysical surveys to test tracer‐based storage estimates in headwater catchments. Hydrol. Process., 30: 4434–4445, which has been published in final form at https://doi.org/10.1002/hyp.10889. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.